Hokenshitsu no Tsumuri-san

Tsumuri Katakura is the school nurse who runs the high school's infirmary... which is good, because she's the one who needs to make use of it the most. Tsumuri has a weak constitution, and constantly tires herself out or faints from doing her day-to-day job. It doesn't help that she's also a space cadet and lazy at heart, so when she's not asleep in the infirmary's bed, she's got it covered in snacks and games. Her younger brother, Kouta, is a student at the school and spends plenty of his free time assisting his sister and unwillingly rescuing her from the demands of adulthood.

(Source: Wonderland Translations)